[Hammarlund] HQ-170 audio

[Richard Knoppow]

----- Original Message ----- 
From: "RAY FRIESS" <rayfrijr at msn.com>
To: <hammarlund at mailman.qth.net>; 
<boatanchors at puck.nether.net>
Sent: Sunday, February 20, 2011 2:54 PM
Subject: Re: [Hammarlund] HQ-170 audio


>
> The audio output of my HQ 170 has become very noisy and 
> microphonic.
> Does anyone have spare audio driver and audio output tubes 
> they would be willing to part with?
> Thanks
>
> Ray  wa7itz

     Are you sure its a tube? Both the driver and output 
tubes run wide open all the time, the volume control is 
before the 6AV6. If the microphonics is not varied by the 
volume control its probably coming from the 6AV6 which is a 
high gain tube. But... make sure there are not bad 
connections around it, poke the circitry and wiggle the tube 
to see if it makes any difference. Sometimes cold solder 
joints or a composition resistor that has cracked  can act 
like this.
     Also, just pull the 6AV6 and see if the noise goes 
away, that will eliminate the output tube.

--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com